According to a criminal complaint, a letter carrier received the suspicious envelope on Monday at an address in the 3600 block of South 262nd Street in Kent. A postal inspector examining the black envelope found that it contained a white powder similar in appearance to dried anthrax.

Writing the court, a Secret Service special agent noted that the names of President Obama’s children – Sasha and Malia – were written on the back of the envelope, and the salutation “Hello Michelle & Girls.” The sender was listed as Jim Sinegal, the co-founder and CEO of Costco.

Searching the envelope, investigators found a letter wrapped in plastic and filled with white powder, the Secret Service agent continued.

“Dear Obama – this is an anthrax sting,” the letter’s author wrote. “If you are scared, either mail Jim Sinegal 864.00 so you can call 911 or tell the Atty General he can have your rights too.”

The letter was signed “Dirty Play Sanchez,” according to charging documents.

Investigators went to Young’s Kent home the following day and took her into custody. She was subsequently identified by the letter carrier as the woman who attempted to mail the letter, the agent told the court.

Young is also suspected of mailing two similar letters to the King County Sheriff’s Office, the agent continued.

The first, addressed to a Sheriff’s Office employee, arrived on April 4 at the Norm Maleng Regional Justice Center in Kent. Young’s home was listed as the return address, and the envelope contained white powder.

“APRIL FOOLS – P.S. I cut in the USPS. Burn COSTCO,” the letter read.

The same day, a similar letter also bearing Young’s address arrived at the King County Courthouse in Seattle, the agent told the court. The letter’s author claimed to have “your Narc dog hostage” and demanded “supplies.”

Both letters appeared to have been hand delivered to the Sheriff’s Office.

Describing an interview with Young, the Secret Service agent contended the woman admitted to delivering the letters.

“Young stated that she put the powder in the letter ‘to piss off Obama,’” the agent told the court. “Upon showing her the letter written to the President, Young pointed out a red fingerprint on the letter and stated that this was her ‘right pointer finger’ and that she had put it on the document.”

Young went on to say she’d been using methamphetamine for several days, and that she attacked her boyfriend while he was sleeping, the agent continued. She said she targeted Costco, the agent said, because she’d been fired from her job with the company and either planned to sue or had already sued.

Federal prosecutors have charged Young with one count of conducting an anthrax hoax. She appeared in U.S. District Court on Wednesday and is expected to return in coming days for a detention hearing.

The powder in the envelopes is believed to have been flour and baby powder. Anthrax attacks in 2001 targeting the U.S. Senate and media outlets killed five people and infected 17 more,